There are more and more users of public networks such as the Internet network who are also customers doing electronic business by ordering articles offered by commercial sites. Electronic payment over a public network is a major issue for customers as well as for the commercial sites. The most secure payment method requires extra equipment be added to the customer machine to read a credit card. Unfortunately, this type of equipment is not widely available. The most common way of payment remains the use of a Secure Socket Layer (SSL) connection between the commercial site and the customer browser. SSL is a protocol that provides privacy over the Internet. However, even with this method, the customer credit card number is still sent over the public network making this information the most desirable data for hackers.
In order to avoid the drawbacks of public networks such as the Internet, another method to conduct electronic business uses SMS messages that can be easily sent from any mobile telephone. But SMS messages have the drawback that the service is generally unsuitable for electronic commerce where a secure and controlled data delivery is required. This problem has been solved by the system described in PCT patent application WO 03/063528 wherein, when an SMS message is transmitted via a cellular transmission network from a sender to a recipient, it is required to acknowledge receipt in a predetermined way and an acknowledgement message is subsequently transmitted to the sender of the SMS message.
Even though the system described above is more secure when using the SMS messages, the customer is still required to pay for the articles ordered on a commercial site by using a credit card. Therefore, the number of the credit card has to be either forwarded to the commercial site with the risks of being uncovered by hackers attacking the database of the commercial server or to be requested by a payment server using the Internet network with the risk of being intercepted by hackers when it is transmitted over the network.